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Replacing Your Audi A4 Accessory Belt Tensioner
 
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Pelican Technical Article:

Replacing Your Audi A4 Accessory Belt Tensioner

Steve Vernon

Time:

1 hour1 hr

Tab:

$70

Talent:

**

Tools:

17mm, 13mm wrench

Applicable Models:

Audi A4 (2002-05)
Audi A4 Cabriolet (2003-06)

Parts Required:

New belt tensioner

Hot Tip:

Don't work on a hot engine

Performance Gain:

Won't leave you stranded at the side of the road

Complementary Modification:

New belt

There are two belts on the Audi A4 1.8 liter engine; the timing belt and the accessory or drive belt. Both belts have tensioners and idler pulleys that are used to keep the belts under a constant tension and running straight over the accessory pulleys. This article will deal with the drive or accessory belt repair and maintenance.

The drive belt is mounted on the front of the engine and is turned by a pulley on the end of the crankshaft. This belt is responsible for running the power steering pump, A/C and alternator.

The drive belt tensioner provides a constant tension on the belt, which is needed to run all of the engine accessories. Over time the tensioner can fail to maintain the proper tension and the belt will start to slip. If this happens it will usually make a squealing noise. The tensioner can also fail by the bearing wearing out - this will cause the belt to wear unevenly and fray along the edges. You should check your tensioner and drive belt every six months for wear, cracking, fraying, delaminating and drying out. If the tensioner is loose or you can wiggle it or if your belt shows any of these signs you should replace them. I recommend you always replace the belt when replacing the tensioner and recommend you buy two belts and always keep an extra one in the car. You don't want to be stranded on the side of the road for the lack of a spare drive belt.

Let the car cool so you don't have to work around a hot engine.

The belt and tensioner are located at the front of the engine.
Figure 1

The belt and tensioner are located at the front of the engine. There is very little room to work but if you take your time you can change the belt and tensioner out without moving the lock carrier to the service position. If you have really large hands or just want more room to work you can move the lock carrier into the service position; just be aware that this will add substantial time to the job. Please see our article on removing the front bumper and moving the lock carrier for additional information. Note: we moved the carrier to the service position for photographic purposes. You can see in the image the tensioner (red arrow) and the alternator (yellow arrow).

You will need to take the tension off of the tensioner to remove the belt and change the tensioner.
Figure 2

You will need to take the tension off of the tensioner to remove the belt and change the tensioner. The tensioner has a "nub" on the top outer portion. You can place a 17mm wrench (red arrow) on this and turn it clockwise. You can now slip the belt off or lock the tensioner in the open position.

Turn the tensioner all the way clockwise and insert a retaining pin between the rotating part and the tensioner base through the locking slot (red arrows).
Figure 3

Turn the tensioner all the way clockwise and insert a retaining pin between the rotating part and the tensioner base through the locking slot (red arrows). If you do not have a retaining pin you can use a 5mm Allen key.

With the tensioner locked you can slip the old belt off.
Figure 4

With the tensioner locked you can slip the old belt off. You can see that this belt is past its good use date and has started to crack around the edges (red arrow).

Use a 13mm socket and remove the three bolts holding the tensioner to the motor (red arrows).
Figure 5

Use a 13mm socket and remove the three bolts holding the tensioner to the motor (red arrows).

This photo illustrates the old tensioner.
Figure 6

This photo illustrates the old tensioner. The new tensioner will come locked in the open position. Install the new tensioner and torque to spec. Make sure to use care when removing the locking pin as the tensioner is under a lot of force.

The new belt will be a tighter fit so you may have to use the 17mm wrench and pull back on the tension as far as possible to get the new belt on.
Figure 7

The new belt will be a tighter fit so you may have to use the 17mm wrench and pull back on the tension as far as possible to get the new belt on. This diagram shows you the proper routing of the belt with the tensioner indicated by a red arrow. Installation is the reverse of removal. Do not forget to check that the belt is sitting fully in the groves of each pulley.






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